Angle-resolved photoemission on the delafossite oxide metal PtCoO$_{2}$
ORAL
Abstract
The delafossite structural series of oxides has recently attracted considerable attention because of the remarkable and varied properties of the compounds in the series. Here we consider the Pt-based $5d$ delafossite oxide PtCoO$_{2}$, the most conductive oxide known [1]. From angle-resolved photoemission and density-functional theory, we show that the underlying Fermi surface is a single cylinder of nearly hexagonal cross-section, with very weak dispersion along k$_{z}$. Despite being predominantly composed of $d$-orbital character, the conduction band is remarkably steep, with an average effective mass of only 1.14$m_{e}$. Moreover, the sharp spectral features observed in photoemission remain well-defined with little additional broadening for over 500~meV below E$_{F}$, pointing to suppressed electron-electron scattering. Together, our findings establish PtCoO$_{2}$ as a model nearly-free electron system and an ideal testbed for elucidating the ultrahigh conductivity in delafossite oxides. [1] Kushwaha P. et al., Sci. Adv. {\textbf 1}, 9 (2015)
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